New bike suggestions Central London - Epping

Hi all, 

I'm just coming out of that fog of having younger kids where it looks like I can get some time on the weekends to ride a mountain bike. I live in central London and have been riding up to Epping Forest on a gravel bike and exploring the gravelly roads and paths, but the trails keep winking at me and when I've tried them on the gravel bike, it hasn't been much fun. 

So what bike for Epping, considering...

1) I have a 40 minute ride to get there along canals and probably slightly longer back.

2) It's muddy as all hell (at the moment and probably 4 months a year). So tyre clearance is important and I'm not sure about rear suspension (and perhaps even a dropper)

3) I'm 48, in pretty good shape, but not particularly flexible and don't want something that's going to rattle me to pieces.

Things I've been thinking of

Discounted Santa Cruz Highball

Discounted Specialized Chisel

Thanks